Sense Amplifier Precharge Circuit for Offset Voltage Compensation
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Solution Overview
Problem
Conventional semiconductor memory devices face challenges in reducing power consumption due to large offset voltages in sense amplifiers, which are exacerbated by variations in transistor threshold voltages, leading to increased charge/discharge current and area overhead.
Innovation Solution
The semiconductor memory device incorporates a sense amplifier with a transistor pair and capacitors to precharge drive transistors and compensate source voltages, allowing for early sensing and reducing offset voltage variations, thereby minimizing power consumption and area overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If trimming data is held at every sense amplifier to reduce offset voltage, then sensing accuracy is improved, but area overhead increases
Solution Approach 1:
The sense amplifier performs preliminary action by generating and storing threshold information in capacitors before actual sensing operations. This pre-computed threshold information is then used during sensing to compensate for offset voltages, eliminating the need for trimming data storage while maintaining sensing accuracy.
Solution Approach 2:
The sense amplifier uses its own internal resources (capacitors and transistors) to generate and store threshold information self-service fashion. The circuit automatically compensates for its own offset voltages using internally generated threshold data, without requiring external trimming data storage resources.
2Area of stationary object
If zeroing method is used to reduce offset voltage by superimposing offset voltage on bit line, then area overhead is reduced, but charge/discharge current increases leading to higher power consumption
Solution Approach 1:
The sense amplifier performs preliminary action by precharging drive transistors and storing threshold information in capacitors before sensing operations. This preliminary preparation allows the sense amplifier to compensate for offset voltages without requiring additional charge/discharge current during normal operation, thus reducing power consumption while maintaining low area overhead.
Solution Approach 2:
The invention changes the operational parameters by introducing precharge operations and capacitor-based threshold storage. This parameter change allows the sense amplifier to compensate for offset voltages through voltage information storage rather than through increased charge/discharge current, thereby reducing power consumption.
3Measurement precision
If sense amplifier sensitivity is intensified to detect small bit line voltage differences, then sensing capability is improved, but offset voltage variations become more significant
Solution Approach 1:
The sense amplifier implements feedback by using stored threshold information to compensate for offset voltages. The threshold information generated from the drive transistors' own characteristics is fed back to compensate for their offset variations, allowing the amplifier to maintain high sensitivity while correcting for manufacturing precision variations.
Solution Approach 2:
The invention changes the electrical parameters by introducing capacitor-based voltage storage and precharge operations. This parameter change enables the sense amplifier to compensate for offset voltage variations through stored threshold information, allowing high sensing capability while mitigating the impact of manufacturing precision variations.
Data Source
AI summary
A semiconductor memory device comprises a memory cell; a first bit line and a second bit line connected to the memory cell; and a sense amplifier operative to amplify the voltage between the first and second bit lines. The sense amplifier includes a first and a second drive transistor configuring a transistor pair for differential amplification, and a first and a second capacitor connected between the sources of the first and second drive transistors and a source control terminal, respectively. The sense amplifier precharges the first and second drive transistors on the drain side prior to sensing, thereby holding the threshold information on the first and second drive transistors in the first and second capacitors, and compensates for the source voltages on the first and second drive transistors by the threshold information held in the first and second capacitors at the time of sensing.